Composition and method for dispersing proteinaceous stains

ABSTRACT

A DETERGENT COMPOSITION IS FORMULATED TO CONTAIN AN AMINOTHIOL OF THE FORMULA HS(CH2)NNH2 WHERE N IS FROM 2 TO 4, A PROTEIN SWELLING ANIONIC SURFACE-ACTIVE AGENT AND A PH BUFFERING COMPOUND. THIS DETERGENT COMPOSITION HAS PARTICULAR UTILITY FOR DISPERSING PROTEINACEOUS STAINS.

United States Patent 3,796,666 COMPOSITION AND METHOD FOR DISPERSING PROTEINACEOUS STAINS Alan Jones, Newcastle-upon-Tyne, England, assignor to The Procter & Gamble Company, Cincinnati, Ohio No Drawing. Filed June 7, 1972, Ser. No. 260,650 Claims priority, application Great Britain, June 15, 1971, 28,016/71 Int. Cl. Clld 1/04, 9/30 US. Cl. 252-110 Claims ABSTRACT OF THE DISCLOSURE A detergent composition is formulated to contain an aminothiol of the formula HS(CH NH where n is from 2 to 4, a protein swelling anionic surface-active agent and a pH buffering compound. This detergent composition has particular utility for dispersing proteinaceous stains.

BACKGROUND OF THE INVENTION Various methods have been tried for removing proteinaceous stains such as blood, egg, various other food residues and the like from surfaces, and especially from fabrics, but none is ideal. Thus, many soaps and detergents, particularly when containing detergency builders and oxidizing bleaches, partially remove some of these stains but they tend to cause damage to fabrics if formulated or used harshly enough to be very effective. Of recent years detergent compositions containing proteolytic enzymes have been developed and they do go some way towards overcoming this problem. Unfortunately, enzymes act rather slowly, and at higher washing temperatures are deactivated. They are also expensive and dependent upon biological processes such as fermentation for their production on a commercial scale- There has now been found a method of treating proteinaceous stains, and substances stained therewith, Without necessarily employing enzymes, whereby the stains are made more readily soluble or dispersible in aqueous or aqueous detergent solutions.

The present invention provides a dispersing composition for proteinaceous stains comprising an aminothiol of the general formula:

HS (CH ),,NH

(in which n is from 2 to 4), a protein-swelling anionic surface-active agent, and one or more pH buffering compounds such that an aqueous solution of the composition containing 0.1 weight percent of aminothiol has pH in the range of 7 to 12.

While the invention does not depend upon any explanation of its mechanism, it appears that the protein-swelling action of the surface-active agent renders the protein stains more susceptible to attack at their disulfide linkages by the sulfhydryl compounds. Thus, the latter are effective in mild conditions and at low concentrations to break the bonds holding together the proteinaceous stains so that they are more readily dispersible by Washing.

A preferred aminothiol suitable for the compositions of the invention is aminoethanethiol (sometimes known as aminothioethanol or cysteamine), which is the compound of the general formula given above in which n is 2.

The compounds of the general formula given above are compatible with anionic surface-active agents and are effective in midly alkaline conditions, for instance, from pH 7 to 12, preferably from 8 to 11.

Suitable anionic detergents are those which have strong protein-swelling tendencies, particularly those with hydrophobic chains of about 12 carbon atoms, such as sodium alkylsulfates having about 8 to 14 carbon atoms, and

3,796,666 Patented Mar. 12, 1974 soaps having the same range of chain length. These may conveniently be derived from coconut fatty alcohols or fatty acids. Alkylbenzene sulfonates having 8 to 13 carbon atoms in the alkyl group, such as those from the common commercial detergent alkylates, are also suitable, but the effect of, for instance, dodecylbenzene sulfonate, is considerably less than that of said alkyl sulfates or soaps. Sodium alkylsulfates are preferred.

Suitable pH buffering compounds are known in the art. It is an advantage of these compositions that many of the compounds suitable as pH buffers are those employed in conventional alkaline detergent compositions, and, whether acting as buffers or not, these compounds may be incorporated in the compositions. Thus, there may be present water-soluble phosphates and polyphosphates, carbonates, silicates, borates, and, if desired, neutral salts such as chlorides, or sulfates. Alkaline organic sequestrant and detergency building salts such as the aminopolycar- 'boxylates such as nitrilotriacetates, or ethane hydroxy diphosphonates and the like may also be used.

The ratio of anionic surface-active agent to aminothiol is not very critical, but is preferably at least 1:2 molar so that enough anionic is present. The upper limit of this ratio is determined by practical and economic considerations and may be as high as 10:1 or more. A generally useful range is 1:2 to 8: 1, but normally a molar ratio of about 2:1 to 1:1 is suitable and convenient.

The proportion of pH buffering agent muct be sufficient to controlthe pH as specified above. When deterency builders are used they can be present in the proportions usual in built detergent compositions, and often as such provide ample pH buffering capacity. The actual level of aminothiol in the compositions can vary widely according to the nature of the composition and the concentration at which it is intended to be used, and the preferred in-use concentrations will be described below.

In addition to the above-mentioned components, reducing bleaching agents may be included in these compositions, but oxidizing agents are incompatible. Suitable reducing bleaches are, for example, sodium borohydride, sodium dithionite and hydrazine hydrate.

Also, nonionic, semipolar or zwitterionic surface-active agents may be included. Suitable nonionic agents include the well-known condensation products of ethylene oxide on fatty alcohols, alkylphenols, fatty acids, fatty amines and sorbitan esters. Semipolar agents are, for example, long-chain tertiary amine oxides or phosphine oxides, such as dodecyldimethylamine oxide. Suitable zwitterionic agents include the quaternary ammonium betaines, sulfobetaines, and sulfatoor sulfito-betaines, for example, octadecyldimethyl ammonio-propane sulfonate or -hydroxypropane sulfonate, and dodecylbenzyl dimethyl ammoniopropane sulfonate.

The compositions may also contain, when appropriate and compatible, the usual minor ingredients of such compositions. These include suds-controlling agents, soil-suspending agents such as carboxymethylcellulose, polymers of maleic anhydride and methylvinylether and the like, enzymes, optical brighteners, tarnish-inhibitors, bacteriostats or bactericides, colors and perfumes.

The invention also embraces a method of dispersing a proteinaceous stain on the substrate stained therewith which comprises treating the stain with an aqueous solution of a composition of the invention while maintaining the pH of said solution in the range 7 to 12 preferably 8 to 11.

In this method, it is preferred to use a composition containing fl-aminoethanethiol.

Preferably there should be at least 2 10- more preferably from 10x10 to 40x l0 gram-moles per liter 3 of aminothiol, and 3x 10 more preferably from 10x10- to 55 X 10- gram-moles of anionic surface-active agent present, and they should be present in molar ratio as defined above. Higher concentrations may be used, the upper limit being again determined by economic considerations.

-In carrying out the method, stained substrates may be treated by soaking or washing them, preferably with agitation, in solutions of the specified strength at temperatures in the usual washing range, for instance, from 10 to 100 C., especially from 20 to 70 C. An overnight soak at about 20 C. (or ambient) temperature is effective. At higher temperatures, stain dispersal can be obtained more quickly. Unlike enzymes, these compounds are not destroyed or rendered ineffective by high temperature up to about 100 C. Thus, they are suitable for use in compositions intended for automatic dishwashing machines where very hot water is commonly employed.

rinsed and washed in freshly prepared test solutions at 50 C., for 10 minutes, in a miniature washing machine. They were then rinsed in soft water and air dried. Their reflectance was measured as above. Percentage stain re moval was calculated as:

Final reflectance-initial reflectance Reflectance of clean fabric-initial reflectance A B C D E F G H .I K

Sodium dodecylbenzene sulfonate 5. 6 5. 6 5. 6 5. 6 5. 6 5. 6 5. 6 5. 6 5. 6 5. 6

Sodium tallow alkyl sulfate 3. 7 3. 7 3. 7 3. 7 3. 7 3. 7 3. 7 3. 7 3. 7 3. 7

Coconut monoethanolarnide 1. 1.0 1. 0 1. 0 1.0 1. 0 1. 0 1. 0 1.0 1.0

Sodium tripolyphosphate 36. 0 36. 0 36. 0 36. 0 36. 0 36. 0 36. 0 36. 0 36. 0 36. 0

Sodium tallow soap 2. 0 2- 0 2. 0 2.0 2.0 2. 0 2. 0 2. 0 2.0 2.0

Sodium sulfate 8. 0 8. 0 8. 0 8. 0 8. 0 8. 0 8.0 8. 0 8. 0 10. 0

Enzyme product (Alcalase 0. 2

Sodium perborate tetrahydrate. 24. 0

Miscellaneous 4. 5 4. 5 5 4. 5 4. 5 4. 5 4. 5 4. 5 4. 5

Moisture (nominal) 7. 0 2 8. 5 2 9.2 9. 2 29. 5 17. 2 31. 2 4. 5 Sodium lauryl sulfate (b) 0 16. 16.0 20. 5 1. 2 0

Sodium coconut soap (c) Aminothiol, g. mol/ltr. X10- 26. 4 26. 4 26. 4 26. 4 36. 0 2. 2 17.5 26. 4 Anionic plus (b) or (c), g. mol/ltr. X10 28. 0 28. 0 35. 0 28.0 6. 6 2. 2 17. 6 28.0 Percent blood stain removal 54-56 85. 0 81. 0 87.0 80. 0 60. 0 2 59. 0 2 77. 0 85. 0

1 Trademark. 2 Two-hour soak. 3 Example 3.

EXAMPLE I EXAMPLE III A standard blood stained test cloth (cotton), so-called EMPA 111 obtained from EMPA, Unterstrasse 11, 9001 St. Gall, Switzerland was given a preliminary wash in soft water at 40 C. and dried.

A solution was prepared containing 1 g. aminoethanethiol and 4 g. sodium lauryl sulfate (approx. equimolar proportions) per liter in soft water with pH buffered to 9.5. A two-inch square piece of the above test cloth was allowed to soak overnight (16 hours) in 1 liter of the above solution, initially at 21 C. but allowed to cool naturally to about C. (ambient temperature). The cloth was then rinsed in soft water and allowed to dry.

A comparative test was made in which the test cloth was treated similarly except in that it was soaked in a solution of 5 g. per liter of a commercial enzymeand perborate-containing heavy-duty anionic detergent composition.

The stain removal by the aminoethanethiol/sodium lauryl sulfate mixture was as good as or better than by the conventional enzymeand peroxy bleach-containing detergent composition.

EXAMPLE II Test method for protein stain dispersion Standard blood-stained cotton fabric (EMPA 111, supplied by EMPA, St. Gall, Switzerland) was pretreated by washing at 40 C. in soft water for minutes. It was rinsed and air dried, and its reflectance measured with an BEL (Evans Electroselenium Ltd.) spectrophotometer using a No. 601 filter.

Test pieces of the pretreated fabric were soaked and/or washed in test solutions of compositions according to the invention and of reference compositions. Test solutions for soaking were prepared, and the test pieces were added, at C., being then allowed to cool naturally during the period of the soak. The test pieces were then The product of composition B of Example II was compared with the same, but omitting aminothiol and sodium lauryl sulfate and replacing with moisture (normal) to make up the formula weight, coded J. In this instance, the. test pieces were given a 10 min. wash, without any soak treatment, at various temperatures, followed by the usual rinse and drying.

Stain removal,

Bleaching agent 0.075

Test pieces as in Example II were given an overnight soak and a 10 min. wash at 60 C.

Stain removal figures were:

Percent (a) Bleaching agent sodium dithionite 97 (b) Bleaching agent sodium borohydride 96 EXAMPLE V A scrambled egg mixture was cooked, but not burnt, on aluminium plates, and after cooling, surplus egg mixture was scraped off manually, leaving as far as practical equal amounts of soiling on each plate.

(A) Fairy Liquid at pH 7 -a household dishwashing composition marketed by P&G Ltd.

(B) As (A) but pH adjusted to 9.5.

(C) 84 parts Fairy Liquid, 16 parts sodium lauryl sulphate, with pH 9.5.

(D) 76 parts Fairy Liquid, 16 parts sodium lauryl sulphate, 8 parts aminoethane thiol hydrochloride.

The cleaning was found to improve in the order composition A to composition D.

What I claim is:

1. A dispersing composition for proteinaceous stains consisting essentially of (a) an aminothiol of the general formula HS (CH NH wherein n is from 2 to 4; (b) a protein swelling anionic surface-active agent; and

(c) a pH bufiering compound selected from the group consisting of water-soluble phosphates, polyphosphates, carbonates, silicates, and borates in an amount suflicient to impart a pH in the range of 7 to 12 to an aqueous solution of the composition containing 0.1 weight percent of aminothiol,

wherein the molar ratio of the anionic surface-active agent to the aminothiol is at least 1:2.

2. The composition of claim 1 wherein the molar ratio of anionic surface-active agent to aminothiol is from 1:2 to 8: 1.

3. The composition of claim 2 wherein the anionic surface-active agent is an alkyl sulfate having 8 to 14 carbon atoms.

4. The composition of claim 2 wherein the anionic surface-active agent is a soap having 8 to 14 carbon atoms.

5. The composition of claim 3 wherein the aminothiol is fi-aminoethanethiol.

References Cited UNITED STATES PATENTS 2,447,860 11/1944 Jones et a1. 106155 HERBERT B. GUYNN, Primary Examiner C. L. ROLLINS, Assistant Examiner US. Cl. XR. 

